Conventionally, there have been proposed various sorts of techniques for forming a microscopic three-dimensional steric shape using mask patterns and light curing resin.
For example, as shown in FIG. 18, a tilt exposure method in which light curing resin 223 on a transparent mask plate 221 on which a mask pattern 222 is formed is exposed to light from different directions as shown by arrows 224a and 224b, and an unexposed portion 224k of the light curing resin 223 is removed to form a steric shape has been proposed (refer to Patent Document 1, for example).
Further, there is disclosed an example of trial production that microstructures which are arrayed to stand together in large numbers in a reticular pattern are processed three-dimensionally as shown in a photograph of FIG. 20 by a rotating tilt exposure method in which a light curing resin (SU-8) and a mask plate are placed on a rotating stage whose central axis is tilted toward a direction of light exposure, to perform light exposure as shown in explanatory diagrams of FIG. 19 (refer to Non-patent Document 1, for example). By devising mask patterns to be used in a rotating tilt exposure method, it is possible to form a nozzle shape, a flow channel structure which is three-dimensionally branched, and the like (refer to Patent Document 2, for example).
As other methods, a direct drawing method for drawing a steric shape while moving a specific light source, a method in combination with a multistage exposure method using many masks, and the like have been proposed.
In a tilt exposure method and a rotating tilt exposure method, it is possible to produce those in a single light exposure, and its number of processes is small and large-scale facilities are not needed, which makes it possible to manufacture a microstructure at low cost in comparison to the other methods.